4. Soil hydrolytic acidity CH3COONa+H2O- CH3COOH NaoH H-Colloid=Al 4CH3 COoNa- Na-Colloid-3Na Al(oh+4CH COoH Oxide -oH+ Ch CooNa-Oxide-o-Na*+ CH COoH4. Soil hydrolytic acidity CH3COONa + H2O CH3COOH + NaOH H-Colloid Al + 4CH3COONa Na-Colloid 3Na + Al（OH）3 +4CH3COOH Oxide -OH + CH3COONa Oxide-O-Na++ CH3COOH